Agricultural equipment of various types and sizes is used to cut vegetation ranging from grass to small trees. Different types of cutting blades are used on the various types of agricultural equipment, and many cutting blades include beveled edges that improve the cutting ability of the blades.
FIG. 1 illustrates a prior art cutting blade 10 having opposite edges 14 and 18 that are at least partially beveled. The portion of the blade 10 shown in solid lines represents a flail-type blade, however, as shown in phantom, the blade 10 could also be a symmetrical rotary cutting blade. As can be seen in FIG. 1, the edges 14 and 18 have symmetrical bevels 22 and 26, respectively, that decline outwardly from the top surface of the blade 10 toward the bottom surface of the blade 10 to define cutting edges 30 and 34 that extend longitudinally adjacent the bottom surface of the blade 10. The bevels 22 and 26 are substantially symmetrical about the blade's longitudinal axis 38.
It has also been known to bevel blades asymmetrically such that the cutting edge on one beveled edge of the blade is adjacent the bottom surface of the blade and the cutting edge on the other beveled edge of the blade is adjacent the top surface of the blade. FIG. 2 illustrates a blade 40 having this configuration. As seen in FIG. 2, the edge 44 has a bevel 48 substantially like the bevel 22 of FIG. 1, while the edge 52 has a bevel 56 that declines inwardly from the top surface of the blade 40 toward the bottom surface of the blade 40 such that the cutting edge 60 extends longitudinally adjacent the top surface of the blade 40. Thus, the bevels 48 and 56 are substantially asymmetrical about the blade's longitudinal axis 64.
Beveled edges can be formed using a variety of machining techniques, including milling, coining, and shearing. When manufacturing the cutting blade 10, both of the beveled edges 22 and 26 can be formed quickly and easily in one machine setup. When manufacturing the cutting blade 40, however, the bevels 48 and 56 on the blade 40 must be machined from opposite sides of the blade 40, requiring two separate machine setups. In other words, after the bevel 48 is machined, the blade must be removed from the machining device, turned over, and repositioned in the machining device before the bevel 56 can be machined. In addition to adding time and expense to the manufacture of the blades 40, this three-step process typically results in the formation of burrs, which dull the beveled cutting edges.
It has also been known to manufacture blades so that the cutting edge is positioned approximately midway between the top and bottom surfaces of the blade. This includes machining oppositely facing bevels on the same edge of the blade so that the two bevels intersect to create the cutting edge at approximately the midway point of the blade's material thickness. This configuration also requires the three-step machining process described above just to achieve the desired configuration for one edge of the blade.
One solution available for manufacturing the blade 40 without the added machining costs is to form the asymmetrical beveled edges during the initial hot-rolling of the metal, or in a secondary hot-rolling process. Blades having midpoint cutting edges can also be formed via rolling. While this rolling process can eliminate the burring and dulling experienced in the three-step machining process, it is still more costly and time consuming than the more efficient machining techniques commonly used to manufacture the bevels.